1. Technical Field
The present invention relates to a power supply circuit and a test apparatus. In particular, the present invention relates to a power supply circuit that supplies power to an electronic device, such as a semiconductor circuit, and a test apparatus that tests an electronic device, such as a semiconductor circuit.
2. Related Art
Conventionally, a power supply circuit is mounted on a test apparatus that tests an electronic device to provide power to the electronic device. The power supply circuit may be provided with a current control function to prevent excessive current flow to the electronic device as in, for example, Japanese Patent Application Publication No. 2007-309859.
The circuit disclosed in FIG. 5 of the above Patent Application Publication detects the current flowing to the device under test by detecting the voltage at both ends of a current detection resistor provided at the output of a main amplifier. When the detected current is outside of a limit range determined by the settings of the DA converter, the power supply circuit controls the current flowing to the device under test to be within the limit range by controlling the voltage supplied to an input end of the main amplifier.
However, even when such a circuit controls the current flowing to the device under test to be within a prescribed range, excessive current that is outside of the limit range transiently flows to the device under test. For example, excessive current flows to the device under test while the circuit gradually changes the current to be within the limit range.
Because of this, a transient excessive current continuously flows to the device under test when a switch in the device under test is quickly turned on or off. When this happens, the circuitry in the device under test is undesirably stressed by heating due to the excessive current.